Booster seat



FIG. 1 is a perspective view from the front, top, and left side of the booster seat embodying my new design;

FIG. 2 is a top plan view thereof;

FIG. 3 is a bottom plan view thereof;

FIG. 4 is a right side elevational view thereof;

FIG. 5 is a left side elevational view thereof;

FIG. 6 is a front elevational view thereof; and,

FIG. 7 is a rear elevational view thereof.

The dotted line portions in FIG. 3 are by way of illustration only and do not form a part of the claimed design. 

CLAIM The ornamental design for a booster seat, as shown and described. 